Compound 1a ((R)-3-(3-fluoro-4-(1-methyl-5,6-dihydro-1,2,4-triazin-4(1H)-yl)phenyl)-5-(hydroxymethyl)oxazolidin-2-one) having the following structure is an oxazolidinone antibiotic and may be used to treat infections by Gram-positive bacteria, and particularly, methicillin-resistant staphylococci (MRSA), vancomycin resistant enterococci (VRE), or the like.

An antibiotic effect of the compound and a method for preparing the same have been disclosed in Korea Patent Application No. 10-2008-0093712 filed by the present inventor. However, since the overall reaction step of the preparing method is long, and column chromatography should be used in most of the purifying processes for each step, such that the method is not appropriate for mass production.